1. Field of the Invention
The present invention relates to a telephone and, in particular, to a portable telephone.
In consideration of use at night, a portable telephone has a device for lighting each key of a keypad from the inside of the portable telephone. In order to improve an appearance quality of the portable telephone, it is preferable that the lighting device lights each key uniformly.
2. Description of the Related Art
FIG. 1 shows an example of a telephone in the related art. The portable telephone 10 has a structure in which a telephone body assembly 11 and a keypad 12 are contained in a case assembly 15 which consists of a combination of a rear case assembly 13 and a front case assembly 14.
The telephone body assembly 11 has a plurality of LEDs (Light-Emitting Diodes) 17, each between adjacent key contacts 16. When it is used at night, a button for lighting is pressed, the LEDs 17 emit light, and the light 18 from the LEDs 17 propagates and diffuses as indicated by arrows shown in FIG. 2 in the keypad 12 which is made of a silicon rubber. Thereby, all key tops 19-1, 19-2, 19-3, . . . are lit from the inside.
As seen from FIG. 2, the light from the LEDs 17 approaches each key top from the side of the key. As a result, it is likely that a portion of the key top nearer a respective LED 17 is brighter accordingly. For example, in FIG. 2, the portions 20 are bright while the portions 21 are dim. With regard to the key top 19-2, for example, as shown in a brightness curve X in FIG. 2, the mid portion is dimmest. With regard to the key top 19-1, the left side portion is dark. With regard to the key top 19-3, the right side portion is dark. Thus, unevenness in brightness occurs in each key top and thus an appearance quality is poor.